1. Field of the Invention
The present invention relates to building structures, and more particularly, to modular prefabricated building structures which can be secured together at a building site to form a building of any desired length.
2. Prior Art
There are many forms of articulated prefabricated buildings which can be collapsed in order to transport them from the fabrication factory to the building site where they are then unfolded, erected and secured to a foundation along with a plurality of other similar units so as to form a building shell of any desired length. Such modular building structures usually are formed of articulated roof and side wall panels all of which are connected when fabricated so that only minor assembly, such as placing support braces etc . . . in position between the roofs and side panels, need be made at the erection site.
Such a building is disclosed, for example, in Philp U.S. Pat. No. 3,296,752 and Harvey U.S. Pat. No. 414,976. These two patents disclose foldable building structures of somewhat different construction, but both are designed to be fabricated in modular form at a factory and then folded until they are transported to a building site where upon they are unfolded and erected to form a building of the desired length.
One problem which exists in all such portable buildings is that they are generally transported by a flat bed tractor trailer or a railroad car, which imposes certain restraints on the configuration both in its overall dimensions and its folded form. The buildings must be collapsible in such a manner as to come within the confines of the tractor trailer or other vehicle in which they are to be transported and should in addition be foldable in such a manner that they can be compatably stacked and secured in position without loss of substantial space due to irregular configurations in this folded position.
Difficulty occurs, for example, when the modules are fabricated in such a manner that in their folded positions there are substantial protrusions which can not be intermeshed with corresponding protrusions on similar modules all of which are stacked on the transporting vehicle. Such construction reduces the number of modules which can be transported by a single vehicle and therefore can substantially increase the cost of transportation and in some cases makes the cost prohibitive when the erection site is a substantial distance from the point of fabrication.
If, for example, the construction is such that two roof panels and two side wall panels are interconnected in such a manner that they are all folded one upon another in an accordian like fashion, as is the case with some conventionally known structures such as those mentioned above, the roof or the side wall panels will extend beyond the main envelope of the folded module and would not be compatable with like folded modules so as to be transportable without substantial loss of space due to this lack of interface. Further, buildings which are fabricated in such a manner as to be folded in an accordian like fashion require substantial manipulation and end-for-end rotation in order to unfold the side walls of the roof panels so that they may be erected and secured to a foundation. Often this requires the use of a crane and the fastening and unfastening of flexible guide lines several times on a single module before it can finally be erected and secured to the foundation. Thus, substantial labor is involved in the erection of such buildings which reduces their competitive advantage over erection of a building at a site in a more conventional manner.
A yet further difficulty associated with the erection of such conventional modular buildings is that after they have been at least partially unfolded so that the roof panels and side wall panels will fall into position as the module is raised by an overhead crane, the construction is such that after the module has been partially raised bracing members must be applied in order to stop further rotation of the roof panels and the side wall panels relative to one another beyond the position at which it is desired to have them erected. This requires substantial work on the module structure as well as further manipulation by the crane operator which is labor consuming, thus again reducing the cost advantage of such prefabricated structures.